Fire extinguishing pistols



June 10, 1958 HQHUTCHINSON 3 FIRE EXTINGUISHING PISTOLS Filed May 13.1954 Inventor mzm Attorneys United States Patent ,4 Ice i "Patented June10, 1958 This invention relates to fire extinguishing pistols of thekind wherein a cartridge containing a fire extinguishing compound orcomposition is fitted into a barrel which may be detachable from thebutt of the pistol for recharging and wherein a spring propelled strikeris released by the operation of trigger mechanism to detonate an.

explosive charge and eject the contents of the cartridge onto a fire.

Experience in the manufacture and use of fire extinguishing pistols ofthe kind above described has shown that their range tends to be limitedby the tendency of the extinguishing mixture tobecome banked up orcompressed thereby increasing the resistance to the action of thepropellant gases. It has also been found that the full pressure of theexplosive gases cannot always be utilised and that these gases tend toescape around the outer surfaces of the extinguishing mixture causingineffective discharge thereof.

The object of the present invention is to provide improvements in theknown construction of fire extinguishing pistols designed to overcomethe difliculties described in the preceding paragraph; to ensure theeffective sealing of the cartridge under all conditions;to protect thecartridge against deterioration; and to ensure the efiective dischargeof the cartridge irrespective of climatic conditions, or the effects ofheavy handling or vibration.

According to the invention a fire extinguishing pistol of the kind abovedescribed is characterised by the provision of means for sealing bothends of the barrel, said means including a bushing at the rear end ofthe barrel adapted in conjunction with the firing pin to prevent escapeof propellant gases and a double swaging at the muzzle end of the barrelto ensure fluid tight engagement with a sealing element.

In carrying the invention into efiect it may conveniently be applied toa pistol having trigger and striker mechanism as described in thespecification of my prior Patent No. 1,861,533 but the invention is notlimited in within the handle 2. Also mounted within the handle 2 is atrigger 11 movable about a fixed pivot 12 against the resistance of aspring 13. For convenience in manufac ture and assembly the casingincluding the handle is formed in two parts secured together by rivetsor the like at the points 14. Y e I Adjacent the arm 4 of the lever thecasing is secured to a cylindrical butt cap 15 in which the rear end ofthe barrel 16 is adapted to be detachably mounted. The barrel consistsof a metal tube whose rear end is secured into an end cap 17 ofcylindrical form closed at its rear end which is formed with acentralaperture 18. The end cap 17 carries projecting studs 19 adaptedto engage in bayonet slots 20 to secure the barrel inposition in thebutt cap 15 which is also formed with a central aperture 21. Fixed intothe aperture 21 is. a bushing 22 having a central aperture through whichpasses a pin 23 which provides a substantially gas tight'closure in thebush between the firing'mechanism and the de tona tor of the cartridgeand which projects through the aperture 18 attherear end of thebarreland at'the opposite end is provided with a head 24 with which thestriker 5 makes contact when the pistol is operated. 'The arrangementabove described is operated in the known manner by rocking the lever arm4 to the position shown in :broken lines in Fig. 1 whereby its end 8rocks the trigger 11 to the cocked position.v Thereafter, a pull exertedon the trigger 11 to rock it in a'clockwise direction releases the lever4-8 and enables the spring 9 to return it;to the full line positionshown in Fig. 1. This movement results in'the striker 5 makinga sharpimpact on the head 24 of which areto 'be extinguished. I The use of. thebushing 22 and'the transmission of the impulse to' detonate the thatrespect as any other mechanism capable of impelling Reference will nowbe made to the accompanying draw- 7 ings wherein: V

Fig. 1 is a sectional elevation of the handle and butt portions of thepistol.

Fig. 2 is a sectional elevation of the barrel.

Figs. 3 and 4 are respectively face and edge views of a wad or disc fordirecting the propellant gases to discharge the fire extinguishingmaterial.

The fire extinguishing pistol illustrated includes a sheet metal casing1 the lower portion of which is formed as a handle 2. Within the casingis mounted a two-armed lever movable about a fixed pivot 3. One arm 4 ofthe said lever is formed integral with a striker 5 and its end 6projects through a slot 7 in the casing and is shaped to facilitatemanual operation to cook the pistol as hereinafter described. Thesecondarm 8 of the lever is connected to a spring 9 Whose other end isanchored at 10 propellant charge through the pin 23 seals'the rear endofthe barrel to prevent leakage and ensurethat subs'tan- 1 tially theentire pressure developed'by; thedetonation of the charge is utilised topropel the cartridge from the barrel. p e

In order to seal the muzzle end of the barrel to prevent deteriorationof the fireextinguishing compound during storage, the arrangements shownin Fig. 2 are employed. To retain the sealing element securely inposition, the muzzle end of the barrel is formed with a double swagingat 25 and 26. Into the annular recess formed by the swaging at 26 isformed the sealing member 27 which is of composite form consisting of acompound ofhigh melting point bitumen held between two discs of cardbeing preferably covered with a coatingof tin or lead foil, andafterwards covered with a coating of paint. The compound for the sealingmember is pre heated to liquid form and pouredover thedisc which restson the inward swaging at 25 until the compound is built up to the'depthof, and fills swaging 2 6, the mouth of the barrel having beenpre-heated to a higher temperature than that of. the liquid'compound'toensure the marrying or adhesion'of the plastic compound to the metal ofthe cylinder,

thereby efiecting a complete air tight'seal which is only broken by thefull pressure created by the explosion of the propellant charge.Compression of the extinguishing mixture and consequent resistance tothe action of the propellant gases is prevented by the introduction intothe cartridge of a compressible and non-caking cushion V 32 consistingof a powder of which kieselguhr is a suitable example. This powder actsnormally as an elastic cushion to prevent the extinguishing mixture 33settling through excessive and continuous vibrations but during thedischargeoperation it acts as an expansion chamber for the propellantgases owing to its, greater compressibility than the extinguishingmixture, thereby acting as a ber of radial slots as shown in Fig. 3initially closed but opened (by the j pressure of the propellant gases.The

central disposition of the slots ensures even and central pressure beingexerted on the extinguishing mixture and thus reduces or prevents thetendency of the propellant gases TQ'BSCHPE around the outer surfaces ofthe extinguishing mixture. After use, the barrel 16 is removed forrecharging with a fresh cartridge and re-sealing.

I claimz 1. In a fire extinguishing pistol having means for ejecting adrypowder fire extinguisher, the combination of a firing pin fordetonating a propellant charge, a striker adapted to engage and operatethe firing pin,a barrel to enclose a cartridge containing the fireextinguishing powder, :1 propellant charge and a detonator therefor, abushing extending from the rear end of the barrel through which thefiring pin passes and arranged to seal the rear end of the barrel toprevent rearward release of pressure created by explosion of thepropellant charge, a double swaging at the muzzle end of the barrel, anda sealing element having at fluid tight engagement with said swaging toprevent deterioration of the fire extinguishing pow: der.

2. A fire extinguishing pistol as defined in claim 1, in

cluding a butt cap in which the rear end of the barrel is engageabledetachably, and wherein said bushing is cylindrical and located at thecentre of the butt cap, the firing pin is longer than and passes throughsaid bushing into the rear end of the barrel and forms a substantiallygas tight closure of the bushing, said detonator is a percussion cap onthe rear end of the cartridge, and the rear end of said firing pin isengageable by pivotal movement of said striker when released by thetrigger mechanism to immediately cause'the forward end of said pintostrike the percussion cap and detonate the propellant charge.

3. A fire extinguishing pistol as defined'inclaim 1, wherein said doubleswaging at the muzzle end of the barrel forms an annular recess backedby an internal 4 shoulder, and said sealing element is composite andsealed into said recess to form an air tight joint.

4. A fire extinguishing pistol as defined in claim 1, wherein saidsealing element 'comprises two discs of card, a layer of plasticcompound located between said discs, and a covering of thin metal foilapplied to the outer disc.

5. A fire extinguishing pistol as defined in claim 1, wherein the fireextinguishing powder is a compressible and non-caking powder to act as acushion to prevent settling of the fire extinguishing powder and to actas an expansion chamber for the propellant gases during discharge.

6. In a fire extinguishing pistol having a butt to receive a barrel forenclosing a cartridge containing a fire extinguishing preparation, apropellant charge and a detonator therefor, a disc of asbestos sheetdisposed between the propellant charge and the fire extinguishingpreparation, said disc being slotted to enable it to open under pressureand ensure the full efiect of the propellant gases being exertedcentrally to cause discharge of the extinguishing preparation, means fordetachably connecting the barrel to the butt ofthe pistol forre-charging the barrel, trigger mechanism, a spring-propelled pivotallymovable striker releasable by the operation of the trigger mechanism todetonate the propellant charge and eject the contents of the cartridge,a firing pin mounted separately from said striker directly engageableand longitudinally movable by the striker, the rear end of said butthaving an aperture about the firing pin, a bushing at the rear end ofthe barrel about said aperture and extending toward said striker andcooperative with the firing pin to seal the rear end of the barrel andsaid aperture to preventrearward escape of pressure created by explosionof the propellant charge, a double swaging at the muzzle end of thebarrel, and a sealing element having a fluid tight engagement with saidswaging to prevent deterioration of the fire extinguishing preparationcontained in the cartridge.

References Cited in the file of this patent UNITED STATES PATENTS789,355 Chisholm May 9, 1905 1,067,803 Daniel July 22, 1913 1,788,443Sedgley Ian. 13, 1931 1,861,533 Hutchinson June 7, 1932

